Chemical manufacture



Nov. 9, 1937. H. D. MUNSON CHEMICAL MANUFACTURE Filed Dec. 4, 1935 NTORm9, Zm-ZM ATTORNEY @atented Nov. 9, i937 STATE earner entice ApplicationDecember 4, N35, Serial No. 52,7188

8 Claims.

This invention relates to safety valves, such as are commonly employedin connection with vessels containing fluids under pressure, and isconcerned more particularly with a device to be used in association withsuch a Valve to protect the working parts thereof against the action ofcorrosive fluids, which results in the sticking of the valve. The newprotective device may be employed advantageously with safety valves ofvarious kinds, and it is especially useful for the protection of valvesemployed on containers for corrosive fluidssuch as liquid chlorine. Forpur- I poses of explanation, therefore, a form of the new protectivedevice. suitable for use with a. safety 15 valve of the type employed onchlorine tank cars will be described in detail, but it is to beunderstood that the utility of the invention is not limited to its-usewith the specific safety valve described, nor to the protection of sucha'valve against the action of chlorine.

- a selected pressure, such as 225 pounds per square inch. There are anumberof dilferent commercial valves employed for the purpose; and inall these valves, the valve seat is exposed to the action of thechlorine, with the result that the 30 valve seat and disc becomecorroded and stick together and the valve does not release untilpressures are generated much higher thanthose for which the valve hasbeen set to operate.

For the purpose of overcoming these. diflicul- 35 ties, it has beenproposed to seal the working parts of t e valve from the fluid, as bymeans of a diaphr gm backed up by a piston which is held in ace by afrangible copper disc. With such a c nstruction, the development of anexcessive pressure in the vessel acts through the diaphragm and pistonto shear or puncture the disc with the result that the fluid is thenadmitted to the valve and causes the latter to 45 open. This proposedexpedient solves the dimfiuid upon the valve, but it has the objectionthat the pressure at which the valve opens is determined by thefrangibility of the copper disc, and 50 it is dimcult to obtain discswhich fracture uniformly and at the same desired pressure.

The present invention is, accordingly, directed to the provision of asafety valve protective device which overcomes the difllculties abovere- 55 ferred to, this device keeping the corrosive fluid cuitiesresulting from the corrosive action of the (@i. geees) from contact withthe valve until a predetermined pressure is generated, and thenfracturing within a small variation from a selected pressure to per--unit the valve to become effective to release the fluid. The deviceincludes .a rupturable closure 5 for the passage through which the fluidis admitted to the working parts of the valve, and this closure, whichmay be a diaphragm of soft metal,

is exposed on one face to the fluid and is supported against rupture bymeans which include 10 a frangible member normally under tension. Uponthe development in the vessel of the selected pressure, the strainplaced upon the diaphragm is transmitted to the frangible member andcauses the latter to break, whereupon the dlaphragm is ruptured and thefluid is admitted through the passage to, the disc of the safety valve.

For a better understanding of the invention, reference may be made tothe accompanying drawing, in which:

Fig. 1 is a view in longitudinal section of a safety valve with theprotective device in place; and

Fig. 2 is a sectional view on the line 2-2 of Fig. 1.

in the drawing, the device is illustrated in connection with a safetyvalve of large discharge capacity, this valve forming no part of thepresent invention. The valve includes a base it) with a flange it bywhich it may be mounted in registry with a suitable aperture in thevessel, and the base carries a housing l2 with a perforated cap 53threaded thereon. Mounted at the upper end of the base is a cylindricalmember is formed at its upper end to provide a valve seat i5 with whichcooperates a valve disc to mounted in a member il sliding in a guidehousing iia. Themember H is forced downward by a spring i8 actingthrough a headed rod E9, the head of which bears upon a plate 20,mounted in the member i'i. The pressure at which the valve opens dependson the compression of the spring l8, which can be adjusted as desired,and when a pressure in excess of the predetermined pressure is generatedbelow the valve disc 86, the latter is forced upward from the seat inthe usual way to permit escape of the fluid.

In order to protect the valve disc and seat fromthe action of thecorrosive fluid, the passage. we in the base of the valve, through whichthe fluid passes from the vessel to the valve disc, is closed by arupturable closure which is normally supported against rupture by meansof 55 a flangible member under tension. When the pressure within thevessel exceeds a predetermined value, the ,flangible member breaks,permitting rupture of the closure, and the fluid thereupon enters thevalve to bereleased by the latter. The means by which the passage forthe admission of fluid to the valve is normally closed. include a plug2| threaded into the base II at the end of the passage Illa. This plughas an Ope ing through it which is closed by a rupturable closure,preferably in the form of a lead disc clamped against a seat formed inthe inner wall.

of the plug by a washer 23 held in place by a member 24 threaded intothe plug against the seat. The member '24 is cup-shaped and it is ofdecreasing diameter from its lower open end to its upper closed end. Thedisc 22 is reinforced by a plate 25, the edge of which is turned to thesame taper as that of the member 24-, the top of the plate being ofsubstantially the same diameter as the inner diameter of'member 24adjacent its upper end. The plate 25 is connected by a plurality of rods26, passing through the upper. end of the cupshaped member 24 to a yoke21. The yoke 21 is connected to the upper end of the cup-shaped member24 by a frangible pin 28, which is of reduced diameter between its ends.This Din may be made of different materials, such as steel, copper, andthe like, and it is so formed both with respect to material anddimensions that it will fracture when subjected to a selected tensileforce.

Under normal working conditions, the diaphragm 22 closes the' lower endof the base of the safety valve, and thus prevents contact of the fluidunder pressure with the working parts of the valve. Corrosion of thevalve parts is thus prevented, and since the fluid does not enter thevalve, minor leaks, resulting inthe case of tank cars from vibration,are avoided. Whenever a pressure develops within the tank or vessel inexcess of the force at which the pinv 28 will break, the transmission ofthis pressure through the ductile diaphragm '22, the rods 26',

and the yoke 21 causes thepin 28 topart at the portion of reduceddiameter. As soon as this occurs, the diaphragm ruptures and the centralportion thereof with theplate 25 is forced upwardly and becomes wedgedin the upper end of the cup 24 above the discharge openings 22. Thecompressed fluid now enters the base of the valve, contacts with thevalve disc it, opens the valve, and escapes in the usual way. Because ofthe relative sizes of the plate 25 and the bore of the member 24, theescaping fluid can act to wedge the plate tightly in position above the.

openings 29, so that the plate will not obstruct the openings.Preferably, the breaking .pin 28 is selected so as to break at apressure slightly less than that at which the safety valve releases,

device has the additional advantage of being relatively sensitive anduniform in operation, this advantage being obtained by the 'use of thebreaking pin as the frangible element. Such .yoke to cause the frangiblepins can be made so that the device will release within a variation offive (5) percent plus or minus of a selected pressure, and thus are notonly much more sensitive and uniform in operation than the frangiblediscs heretofore proposed, but also cheaper.

I claim:-

1. A protective device for closing a passage against the flow of a fluidunder pressure which comprises a rupturable diaphragm closing saidpassage and exposed on one face to said fluid,

and means normally out of contact with said ,sure to be released by saidvalve, comprising a rupturable diaphragm closing said passage andexposed on one face to said "fluid, and means for supporting saiddiaphragm against rupture including a plate contacting with the otherface of said diaphragm, a hollow frame with a tapering inner bore, saidplate beingmovable into said frame upon rupture of said diaphragm andhaving a tapering edge corresponding to the taper of said bore, and afrangible element operatively connected to said plate and frame, saidelement being normally under tension and preventing movement of saidplate which would permit said diaphragm to be ruptured.

3. A protective device for closing a passage against the flow of a fluidunder pressure which comprises a rupturable diaphragm closing said p s eand exposed on one face to said fluid, and means on the other side ofsaid diaphragm and normally out of contact with said fluid forsupporting said diaphragm, said means including a frame, a platecontacting with the face of the diaphragm not exposed to the fluid, ayoke; a frangible element connecting said frame and yoke, and meansconnecting said plate and yoke to cause the frangible element to besubjected to tension.

4. A protective device for closing a passage against the flow of a fluidunder pressure which comprises a rupturable diaphragm closing saidpassage and exposed on one face to said fluid, and means on the otherside of said diaphragm and normally out of contact with said fluid forsupporting said diaphragm, said means including a frame mounted in saidpassage beyond the diaphragm and havingopenings through it, a

plate contacting with the face of the diaphragm not exposed to thefluid, a yoke beyond said frame, a frangible member connecting said yokeand frame, and means connecting said plate and element to be subjectedto tension.

5. A protective device for closing a passage against the flow of'a fluidunder pressure which comprises an annular seat extendingcircumferentiaily of said passage, 9, rupturable diaphragm having itsperiphery resting on said seat, said,

diaphragm closing said passage and being exposed on one face to saidfluid, a frame engaging the other face of said diaphragm and holdingnormally out of contact with said fluid forsupporting said diaph agm,said means including a frame, a plate within the frame contacting withthe face of the diaphragm not exposed to the fluid, a yoke beyond theend of the frame, a frangible element connecting the yoke and frame, anda member extending through said frame and connecting said plate and yoketo cause the frangible member to be subjected to tension.

7. A protective device for closing a eagainst the flow of a fluid underpressure which comprises a plug mounted 'in the wall of the passage andhaving an opening through it, a

rupturable diaphragm mounted in the opening through, said plug andclosing said passage, said diaphragm being exposed on one face to saidfluid, and means on the other side of said diaphragm and normally out ofcontact with said 5 fluid for supporting said-diaphra m, said meansincluding a frame mounted in said plug, a plate contacting with the faceof the diaphragmnot exposed to the fluid, a yoke, a frangible elementconnecting said yoke and frame, and means con- 10 necting said plate andyoke and causing the frangible member to be subjected to tension.

8. A protective device for closing a passage against the flow of a fluidunder pressure which comprises a rupturable closure for said passage 15having a face in contact with the fluid, and means normally out ofcontact with the fluid for supporting the closure against rupture, saidmeans including a frangible member subjected to a pulling strain bythepressure of the fluid act- 20' ing through said closure.

' Homer: 1). mmsou.

